The present invention relates generally to a shaft assembly for ball-type constant velocity joints. Ball-type joints are widely used, for example, in the field of motor vehicle wheel shafts. A joint such as this generally comprises a bell socket connected firmly to a first shaft and a central element secured to a second shaft and housed in the bell socket.
The bell socket and the central element each have six runway tracks distributed at equal angles, on their interior and exterior surfaces respectively. A ball is housed in each pair of tracks so as to transmit torque from the central element to the bell socket and so as to allow the joint to articulate during operation.
A cage fitted between the bell socket and the central element prevents the balls from escaping. The central element is firmly fixed in terms of rotation on the shaft by associated splined profiles. Axial attachment of the central element is achieved in a first direction by stop surfaces, for example a shoulder of the shaft against which the central element abuts. In the second direction, the central element is retained by a split ring housed in a groove formed in the shaft.
This conventional assembly has several drawbacks. For example, between the split ring and the central element or between the central element and the stop surfaces there is a clearance which allows the central element a small axial movement. This leads to the generation of noise while the joint is in operation. In order to keep this clearance as small as possible, close tolerances are needed, which is expensive from a manufacturing standpoint.
In addition, the split rings are relatively complicated to mount and this mounting is difficult to automate because of the precision required in positioning the ring. In addition, in instances where the ring is covered by the central element, there is a problem of groove accessibility at the time of mounting and/or removal.
Furthermore, because the split ring is located inside the joint, there is problem with accessing this ring when the central element needs to be removed.
An object of the invention is to provide an assembly which will simply and reliably eliminate any axial play, particularly in the aforementioned application.
The foregoing and other objects are obtained by an assembly comprising a shaft and a female part which is fixed in terms of rotation on the shaft by rotational-fixing means which cooperate by having complementary shapes. The female part is also fixed axially on the shaft. The female part comprises axial stop means which cooperate with associated stop means belonging to the shaft. The stop means act in the direction of mounting. The female part further comprises axial-retention surfaces cooperating with associated axial-retention surfaces belonging to the shaft. The retention surfaces act in the opposite direction to mounting. The retention surfaces are arranged beyond said associated means in the direction of mounting and cooperate through complementary shapes.
Another object of the invention is to provide a ball-type joint comprising an assembly as defined hereinabove, and a female part intended to be used as the female part of an assembly as defined hereinabove.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.